For a compressor like an aircraft turbine or an industrial compressor of a gas turbine engine with relatively high compression ratios of greater than 15 to 1 it may be typical for the rear static vanes to be held in a floating carrier. The carrier may be mounted in an outer pressure casing by means of radial pins to allow for compensation of thermal expansion.
Bore-scope access through aligned holes in the outer casing and the inner carrier is required for inspection of blades and vanes of the compressor. In normal operation these holes are sealed to eliminate air loss and air recirculation. As large access ports in the outer casing or even removal of the outer casing has to be avoided the inner plug has to be removed and securely refitted via a small access port in the outer casing.
U.S. Pat. No. 4,470,735 shows a self locking bolt where the locking device is a expanding snap ring.
U.S. Pat. No. 3,139,134 discloses a locking device comprising a flexible strip at a location of the circumference of the bolt.
U.S. Pat. No. 5,115,636 and U.S. Pat. No. 4,815,276 show spring loaded bore-scope plugs.
U.S. Pat. No. 5,079,910 shows a spring loaded spherical sealing element used in an inspection aperture. The sealing element is pushed aside to give way for the inspection device.
U.S. Pat. No. 5,152,662 discloses a pivoting flap which controls the access to the inspection port.
U.S. Pat. No. 5,879,116 and U.S. Pat. No. 2,852,056 show resilient locking devices used as inserts on screws.
U.S. Pat. No. 4,825,642 discloses a bore-scope plug comprising a seal locked by a screw on its arm.
U.S. Pat. No. 5,897,277 shows a self locking plug with a spring loaded self locking mechanism.
GB 1 579 730 shows a self-locking spring loaded fastener.
The known solutions require large access ports in the outer casing and/or special headed screwed plugs or bayonet plugs on the internal carrier.